Project Summary Alcohol use disorders affects 8.5% of the US population and currently available therapeutic options are unsatisfactory. Improving our understanding of the neurobiological mechanisms driving excessive drinking is a prerequisite for the development of more efficient treatments. Previous research has indicated that matrix metalloproteinases (MMPs) may be implicated in the etiology of ethanol dependence. The effect of chronic ethanol exposure on MMP activity in the brain is however unknown, and the mechanism linking MMP activity to excessive ethanol consumption remains to be determined. In the present proposal, we seek to characterize the time-course and regional selectivity of MMP activation in the brain of mice escalating their ethanol intake as a result of dependence. In addition, we will test the hypothesis that upregulation of MMP-9 activity in the medial prefrontal cortex contributes to the increased spine density and excessive ethanol consumption triggered by chronic intermittent ethanol exposure. To achieve these goals, we will employ a validated mouse model of dependence-induced drinking escalation, along with in situ zymography, immunohistochemistry and DiOlistic labeling of neurons. Local silencing of MMP-9 expression will be achieved by RNA interference. The proposed experiments are intended to lay the groundwork for future investigation of the mechanisms mediating the upregulation of MMP-9 activity in ethanol dependence. As such, they are expected to carve out a line of research the Applicant may pursue independently as she progresses in her academic career. Completion of the proposed work will enable the Applicant to acquire novel conceptual knowledge and technical expertise pertaining to mouse models of ethanol drinking and dependence, stereotaxic surgery, viral vectors and in situ hybridization. This research will be conducted in an environment (institute and mentors) with a proven track record of training successful fellows.